Anyone Else Catch that Wild “Steaming” Snow Last Night?

On my walk home from work last night, I noticed what I found to be a bizarre phenomenon. It was quite foggy which created an eerie, yet cool atmosphere. Then, as I was walking east on H street NW, heading towards 7th street, I noticed that most of the snow banks had steam billowing from them. It was much in the same way that you see steam come off of an athlete’s head in the cold weather. The pictures don’t quite do it justice, but you can definitely see it a bit (one of the pics looks like exhaust). Now I barely passed high school chemistry, but if a snow bank was steaming, wouldn’t that mean that the snow would have to be warmer than the air?”

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Yes! I saw that and I’m glad you brought it up. Reminded me of the manure piles of my youth. Except not, because it’s not warmer than the air.
Looking forward to the explanation from one of our scientifically savvy posters.

This has been happening as the air has gotten much warmer and more moist over the last few days. Water vapor in the air condenses into the cloud you see when it is cooled by coming close to the snow and ice on the ground.

I also did a bit of a double take when I saw the clouds of fog over the snow banks over the last couple days. But you’re right in observing that it can’t be steam coming from the snow since the snow is cold, not hot like boiling water. The difference here is that the water vapor hanging in the air as a little mini cloud above the snow banks is actually water that started in the warm humid air and is condensing after the snow makes the air colder. Warm air is able to hold more moisture than cold air (http://www.engineeringtoolbox.com/moisture-holding-capacity-air-d_281.html), so when the snow cools down the air directly surrounding it, that water has to go somewhere. This is the same phenomena that’s responsible for forming clouds in the atmosphere. (http://www.weatherwizkids.com/weather-clouds.htm)

I saw crews still hauling away snow piles on 14th street last night. I don’t see the point: The snow is rapidly melting or getting rained on. For what purpose would you put in the manpower and money to haul away snow that is only a day or two away from completely melting? These were not large snow banks, by the way.

A few days after the blizzard in 96′ the same thing happen albeit while we still had over a foot of snow on the ground all over. I literally watch a foot of snow melt right before my very eyes. Of course that set off major flooding coming down the Potomac from Great Falls. Georgetown, Haines Point and Old Town were a mess.